A stent is a medical device introduced into a body lumen and is well known in the art. A stent may be delivered in an unexpanded state to a desired location in a bodily lumen and then expanded by an internal radial force. Stents, grafts, stent-grafts, vena cava filters, expandable frameworks, and similar implantable medical devices, collectively referred to hereinafter as stents, have included radially expandable endoprostheses, which have been used as intravascular implants capable of being implanted transluminally.
Esophageal stents have been used to treat patients suffering from a range of malignant and non-malignant diseases. Most commonly, esophageal stents have been associated with the treatment of esophageal cancers. Esophageal stents have also been used to reduce symptoms resulting from non-esophageal tumors that grow to obstruct the esophagus and to treat benign esophageal disorders, including but not limited to refractory strictures, fistulas and perforations. In each of these cases, esophageal stents may provide mechanical support to the esophageal wall and may maintain luminal patency. Because of the structure of the esophagus and conditions such as peristalsis, esophageal stents have been prone to stent migration.
One way to reduce the risk of stent migration has been to expose bare metal portions of the stent to esophageal tissue. The open, braided structure of the stent may provide a scaffold that promotes tissue ingrowth into the stent. This tissue ingrowth may aid anchoring the stent in place and may reduce the risk of migration. In some cases, however, tissue ingrowth has been known to lead to reocclusion of the esophagus. In addition, esophageal stents anchored by tissue ingrowth cannot be moved or removed without an invasive procedure. To reduce tissue ingrowth, stents have been covered with a coating (e.g., made of a polymer, etc.) to create a physical barrier between the lumen and the esophageal wall. However, in some circumstance, such stents can have an unacceptable occurrence of migration, as compared to bare metal counterparts.
Another way to reduce the risk of stent migration has been to use a flared stent in the esophagus. However, stents having flares can have an unacceptable occurrence of migration.
Granulation tissue caused by stents (e.g., endoprostheses) may occur due to repeated trauma to a wall of a body lumen (e.g., a gastrointestinal wall, a tracheal wall, etc.) and due to subsequent lack of proper wound healing. In some circumstances, granulation tissue, especially in excess, can not only impede flow of solids and/or fluids (e.g., liquid and vapor) through the body lumen (e.g., mucous clearance, air movement, fluid movement, etc.) due to the reduction in the body lumen cross-sectional area (e.g., reduction in radius, etc.), but also because the granulation tissue has a tendency to latch onto the endoprosthesis, which may increase the difficulty of removing the endoprosthesis when necessary. Physician preference has trended toward endoprostheses that are removable and atraumatic.
Improved stents with, for example, improved resistance to migration, improved stent adhesion to the esophageal wall, and/or improved removability are desired. Previous tracheal stents, such as those discussed in US Patent Publication Nos. 2006/0069425 and 2009/0062927, which are incorporated by reference herein in their entireties, have incorporated bumps or other surface features into the stent itself. Another tracheal stent described in co-owned US Patent Publication No. 2012/0035715, which is incorporated by reference herein in its entirety, also provides a plurality of surface protrusions on the outer surface of the stent.
Without limiting the scope of the present disclosure, a brief summary of some of the claimed embodiments is set forth below. Additional details of the summarized embodiments of the present disclosure and/or additional embodiments of the present disclosure may be found in the Detailed Description of the Invention below. A brief abstract of the technical disclosure in the specification is also provided. The abstract is not intended to be used for interpreting the scope of the claims.